Abstract: A system for acoustically imaging a target region behind an acoustically reflective layer includes a transducer configuration for acquiring acoustic image data from the reflective layer and target region, wherein the reflective layer and target region are divided into voxels circumferentially disposed about a central point. The system includes a mechanism for processing the data comprising a transmitting transducer for transmitting a first acoustic pulse, a receiving transducer for detecting a first arrival of a first acoustic reflection signal associated with the first acoustic pulse, and a mechanism for suppressing multiple reflected signals from the acoustic reflection signal associated with the first acoustic pulse, wherein the suppressing mechanism facilitates the acquisition of image data from the target region.

Abstract: This invention provides a closed-loop system for in situ testing of formation fluid conditions and for selectively collecting substantially mud filtrate free formation fluid samples at original formation conditions. The system contains an elongated member having a probe that is sealingly placed against the wellbore formation to withdraw formation fluids. A surface controlled pump controls the flow of a fluid from the formation into a flowline placed in the elongated member. A pressure sensor provides downhole hydrostatic pressure and an acoustic density cell provides the speed of sound in the fluid, acoustic impedance of the fluid and acoustic absorption coefficient of the fluid in the flowline. The system determines the density and compressibility of the formation fluid in the flowline from the speed of sound in the fluid and acoustic impedance of the fluid. The formation of the bubbles are identified or detected from the acoustic absorption coefficient of the fluid in the flowline.

Abstract: Disclosed is a sonic well tool for performing acoustic investigations of subsurface geological formations penetrated by a borehole. The well tool generally includes a longitudinally extending body for positioning in said borehole. The tool also includes a transmitter supported by the body for transmitting acoustic energy, and a receiver supported by the body for receiving acoustic energy. Finally, the tool includes an acoustic attenuation section positioned on the body between the transmitter and the receiver. This section includes one or more cavities defined by the body, inertial mass members positioned inside the cavities in a suitable manner to form a gap between the wall of the cavity and the inertial mass members, and an acoustical attenuation fluid in the gap. The method for attenuating sonic waves generally includes transmitting a sonic wave from the transmitter to the tool, passing the sonic wave through the acoustic attenuation section, and receiving attenuated wave at the receivers.

Abstract: An improved transmission line network includes a transmission line connecting a signal source to a plurality of capacitive loads. Preferably, the transmission line is not terminated with its characteristic impedance. The transmission line may include capacitance added for the purpose of smoothing the rising or falling edge of signals distorted by reflections from the far end of the network. In addition, the transmission line network preferably includes resistance added in series with the transmission line for the purpose of dissipating reflections from the far end and thereby reducing distortion upstream from the series resistors. The capacitive loads may be connected to the transmission line through series resistors, the magnitudes of which are selected to obtain uniform rise or fall times at all loads.

Abstract: A distributed transmission line network for connecting a plurality of DUTs to a low-power driver includes a plurality of distributed transmission lines with distributed capacitors. The distributed capacitors are added to the distributed transmission lines to make the propagation delay on each line equal, thereby eliminating skewed input signals to the DUTs. The capacitors also minimize capacitive cross-talk between the plurality of distributed transmission lines. The distributed transmission line network includes a driver with an internal resistance that is much less than the characteristic impedance of the distributed transmission line to minimize the voltage drop at the driver. The distributed transmission line also includes an input RC network for speeding rise time and a termination RC network for minimizing reflections in the distributed transmission line.

Abstract: The present invention is directed to an apparatus and method for obtaining azimuthally dependent measurements for evaluating the casing cement bond quality and, more particularly, for detecting and specifically locating channels or fissures between the casing and cement. The quality of the bond behind one or more arcs of known location on the casing is determinable by the present invention. The apparatus and method of the present invention employ a plurality of sonic transducers disposed in near contact with the casing in defined segmented locations about or around the exterior surface of a downhole tool. The transducers are arranged in a plurality of arrays, each array comprising four transducers, two transmitting and two receiving transducers, disposed along a single arc about or around the exterior of the tool.

Abstract: The present invention relates to an apparatus and method for calipering a borehole using acoustic measurements within the borehole. These acoustic measurements are useful for measuring the reflectivity of the side walls of a borehole and for calipering a borehole in a wireline or measurement while drilling configuration. The apparatus comprises at least one acoustic transceiver disposed on a calipering tool, together with a second acoustic receiver disposed longitudinally a selected distance from the first receiver. Further, a second acoustic transceiver is disposed on the caliper tool azimuthally from the first transceiver. Measurement of the travel times of acoustic pulses reflected from the borehole walls by the transceivers and receivers of this device, together with other known data, permits an accurate caliper of the borehole to be produced.

Abstract: An electrode insulated from and mounted to the outside of a drill collar in a drill string positioned in a borehole is used for measuring formation spontaneous potential. A current measuring device, such as an ammeter, is connected through a varible ammeter resistor and a switch between the electrode and the drill collar. The ammeter measures current flow from the formation along the walls of the borehole to the drill string to determine the spontaneous potential of the formation at various points along the borehole while it is being drilled. The switch in the ammeter circuit is interrupted at a pre-selected rate and the ammeter current signal is connected through a lock-in amplifier to cancel random noise in the signal and produce an accurate measurement of the very small currents flowing between the electrode and the drill collar. The currents are indicative of spontaneous potentials in the formation.

Abstract: An apparatus and method for measuring fluid characteristics, particularly useful in performing measurements in remote and severe environments is disclosed. The probe employs an ultrasonic transmitter and receiver, preferably a unitary ultrasonic transducer to both transmit and receive the ultrasonic signal. Further, the probe includes an internal reference reflecting surface hermetically sealed from contact with the fluid and one or more solid/fluid reflecting surfaces as are required. Preferably, two solid/fluid reflecting surfaces are located on opposite sides of a fluid receiving gap. The apparatus and method are useful in measuring fluid characteristics both at remote surface and in downhole drilling locations.

Abstract: Method and apparatus for measuring the flow velocity of drilling mud returning from the annulus of a borehole. At least two parametric acoustic pulse transducers are longitudinally disposed with respect to a conduit with a pair of acoustic receivers positioned therebetween. The transducers each generate strong, focused acoustic waves comprised of combined dual frequencies directed at the center of the conduit area in which fluid flow is to be measured. The transducers are actuated alternately and produce time variant signals permitting measurement of fluid flow by employing the Doppler effect on the parametric secondary acoustic pulses. The utilization of combined dual frequency acoustic transducers provides a primary signal having sufficient strength to produce a non-linear response in the liquid and produce secondary, low frequency wave propagation directly from within the mud itself. The low frequency waves enhance wave propagation through gas cut muds and enhance signal recognition in the receivers.